02 Commercial Ship & Fluiddynamics
Our services for commercial ship design and fluiddynamics.
Hull design
ACT offers the service for hull form design and development of commercial ship superior in performance having low drag and good propulsion efficiency by use of CFD while satisfying design restrictions. We have the longest design experience by CFD started in 1993 and also have lots of know-hows and achievements. CFD can reduce the development cost and time evaluating various hull forms before tank testing.
Our service has been provided to ship building and shipping companies since 2006. We have achieved 3 to 15% reduction in BHP at every design compared with existing ship. The fuel consumption of the following bulk carriers per day is around 20-50 ton/day and then the reduction by 5% corresponds to 1-2.5 ton/day.
The past designs include the following;
Hydrofoil catamarans with the foil system design
37m type launched in 2021 is now in commercial service in Zamami, Okinawa
30m type launched in 2017 is in commercial service in Nagasaki
CTV (Crew Transfer Vessel) hull design
Hull designs of more than 30 bulk carriers ranging from Handy size to Cape size
Hull designs of more than 20 containers ranging from 1000TEU to 9300TEU
Consultancy on fluiddynamics
ACT offers a wide range of consultancy services to support the client for the optimum solution to various kinds of fluiddynamic problems. CFD is one of the strong tools to analyze the flow of a fluiddynamic problem and we have various experience and know-hows to adopt CFD to each problem effectively.
Our achievements for the range of consultancy services include the following;
Development of an autonomous yacht unattainable by humans for everBlue technologies. It adopts the generative design and 3D printing technologies.
The wing sail design and performance prediction by CFD and EPP(Energy Prediction Program) for the Wind Challenger project since 2009 as a start-up member. It has been clarified that the averaged BHP reduction is over 20% and if the wind speed is 20kts and the direction is from 90deg to the hull the reduction attains about 50%.
Developments of various new devices to reduce the BHP by improving the propulsion efficiency in the stern region. The stator fins installed on the propeller boss of a bulk carrier reduce the BHP by about 5%.
Analysis of the wind pressure drag on the superstructure of a container and PCC ship and development of a new shape to reduce the drag by more than 20%.
Unsteady CFD analysis to clarify the mechanism of the SRD device developed by SHIMANO INC. for the rowing boat foot stretcher.
Software development & consultancy
ACT has developed various kinds of software to improve design work efficiency. Some of the software has been provided to clients for their design work. We also support the system integration for the design-by-CFD by developing and customizing design software and providing necessary training for effective usage.
Our served software includes the following;
CFD and FEM interaction system
Waterbag deformation prediction software can simulate the towed waterbag deformation due to static and dynamic water pressure. The CFD and FEM iteration technique is used.
SpinFlow software can simulate the flow around a spinnaker and a main sail on a sailing yacht. The flying sails should deform according to the air pressure. The dynamic deformation of the sails can be achieved by FEM as a function of the SpinFlow. The iterative work between the CFD and the FEM can be automatically carried out until the deformation has converged. The GUI is provided for the pre and post processes in which the mesh is automatically created. The results are also visualized in the post process functions.
ParaFlow software can simulate the flow around a parachute to evaluate the fluid dynamic forces acting on the surface. The system is very similar to the above SpinFlow. The boundary conditions for the ventilation and the permeable areas can be set easily on the view window of the GUI.
HullDes/AutoDes software
HullDes/AutoDes has been developed by ACT in collaboration with NMRI. It is the program to support the hull design by CFD. HullDes has limited functions of AutoDes.
The principal functions include the following;
Reading of multiple NURBS hull surfaces in srf format (FastShip) or IGES format.
Hydrodynamic calculation.
Parametric hull form change (changes of principal particulars, Cp, LCB, Frame line, local shape etc) and output of the new surface into the srf or IGES file.
Box type hull form change in a specified area.
Automatic generation of O-H/O-O type structured mesh for CFD.
Mesh generation with the functions of free surface clustering and special treatments to transom stern.
Parallelized grid generation program by OpenMP.
Direct CFD (Neptune Surf and Nagisa developed by NMRI) link.
Hull form optimization by the automatic hull form deformations and the original discretized SQP method.(article_2013)
Data transfer function from IGES to NAPA format.
Overset grids generation for the hull with rudders, fins, stator fins, rudder fins and ducts.
Automatic function for multiple processes from the hull form deformation to the CFD calculaton.
The software has been used by more than 20 ship building and consultancy companies.
For more information please contact to the NMRI.
